Page 8 - Combined_41_OCR

VIBRATION TESTING

Fig. 6—Relative amplitude response
Relative Response frequency ratio. The useful region
of an accelerometer as a function of
of an undamped accelerometer is to
about one-fifth of its natural fre­
quency. For example, a 50-KHz ac­
celerometer permits linear ("flat”)
measurement of vibration frequencies
0.5 to 10 KHz.
0.04 0.06 0.08 0.1 0.2 0.4 0.6 0.8 1.0 2.0
Frequency Ratio, f/fN

e VIBRATION METER £ &

MODEL N524

Typical vibration-measuring equipment. A tiny crystal
accelerometer measures the vibration. The accelerometer
signal might be boosted by a charge amplifier, before being
displayed on an electronic voltmeter. The voltmeter is a
product of MB Electronics, a Textron Co.; accelerometer and
charge amplifier are produced by Endevco Corp.

122 Machine Design